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PowerPC: fix backtrace to handle signal trampolines

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This patch fixes backtrace for PPC32 and PPC64 to correctly handle
signal trampolines. The 'debug/tst-backtrace6.c' also check for
SA_SIGINFO handling, where is triggers another vDSO symbols for PPC32.
This commit is contained in:
Adhemerval Zanella 2013-08-20 15:01:59 -05:00
parent c980f2f4fe
commit d400dcac5e
8 changed files with 172 additions and 6 deletions
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17
ChangeLog
View file

@ -1,3 +1,20 @@
2013-07-23 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
[BZ #15867]
* sysdeps/powerpc/powerpc32/backtrace.c (__backtrace): Handle signal
trampoline stack frame information.
* sysdeps/powerpc/powerpc64/backtrace.c (__backtrace): Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
(__vdso_sigtramp_rt64): New variable: PPC64 signal trampoline.
(__vdso_sigtramp32): New variable: PPC32 signal trampoline.
(__vdso_sigtramp_rt32): New variable: PPC32 signal trampoline.
* sysdeps/unix/sysv/linux/powerpc/init-first.c
(_libc_vdso_platform_setup): Initialize the signal trampolines.
* debug/tst-backtrace5.c (fn): Add an option set modify sigaction
sa_flags value.
* debug/tst-backtrace6.c: New file: check backtrace for signal frames,
interrupting a syscall and set with option SA_SIGINFO.
2013-08-20 Joseph Myers <joseph@codesourcery.com>
[BZ #15531]

4
debug/Makefile
View file

@ -130,16 +130,18 @@ CFLAGS-tst-backtrace2.c += -funwind-tables
CFLAGS-tst-backtrace3.c += -funwind-tables
CFLAGS-tst-backtrace4.c += -funwind-tables
CFLAGS-tst-backtrace5.c += -funwind-tables
CFLAGS-tst-backtrace6.c += -funwind-tables
LDFLAGS-tst-backtrace2 = -rdynamic
LDFLAGS-tst-backtrace3 = -rdynamic
LDFLAGS-tst-backtrace4 = -rdynamic
LDFLAGS-tst-backtrace5 = -rdynamic
LDFLAGS-tst-backtrace6 = -rdynamic
tests = backtrace-tst tst-longjmp_chk tst-chk1 tst-chk2 tst-chk3 \
tst-lfschk1 tst-lfschk2 tst-lfschk3 test-strcpy_chk test-stpcpy_chk \
tst-chk4 tst-chk5 tst-chk6 tst-lfschk4 tst-lfschk5 tst-lfschk6 \
tst-longjmp_chk2 tst-backtrace2 tst-backtrace3 tst-backtrace4 \
tst-backtrace5
tst-backtrace5 tst-backtrace6
tests-ifunc := $(stpcpy_chk strcpy_chk:%=test-%-ifunc)
tests += $(tests-ifunc)

11
debug/tst-backtrace5.c
View file

@ -28,6 +28,10 @@
#include "tst-backtrace.h"
#ifndef SIGACTION_FLAGS
# define SIGACTION_FLAGS 0
#endif
static int do_test (void);
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"
@ -91,7 +95,7 @@ handle_signal (int signum)
}
NO_INLINE int
fn (int c)
fn (int c, int flags)
{
pid_t parent_pid, child_pid;
int pipefd[2];
@ -100,12 +104,13 @@ fn (int c)
if (c > 0)
{
fn (c - 1);
fn (c - 1, flags);
return x;
}
memset (&act, 0, sizeof (act));
act.sa_handler = handle_signal;
act.sa_flags = flags;
sigemptyset (&act.sa_mask);
sigaction (SIGUSR1, &act, NULL);
parent_pid = getpid ();
@ -131,6 +136,6 @@ fn (int c)
NO_INLINE static int
do_test (void)
{
fn (2);
fn (2, SIGACTION_FLAGS);
return ret;
}

21
debug/tst-backtrace6.c Normal file
View file

@ -0,0 +1,21 @@
/* Test backtrace and backtrace_symbols for signal frames, where a
system call was interrupted by a signal.
Copyright (C) 2013 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#define SIGACTION_FLAGS SA_SIGINFO
#include <debug/tst-backtrace5.c>

66
sysdeps/powerpc/powerpc32/backtrace.c
View file

@ -18,6 +18,9 @@
#include <execinfo.h>
#include <stddef.h>
#include <string.h>
#include <signal.h>
#include <bits/libc-vdso.h>
/* This is the stack layout we see with every stack frame.
Note that every routine is required by the ABI to lay out the stack
@ -35,6 +38,46 @@ struct layout
void *return_address;
};
#define SIGNAL_FRAMESIZE 64
/* Since the signal handler is just like any other function it needs to
save/restore its LR and it will save it into callers stack frame.
Since a signal handler doesn't have a caller, the kernel creates a
dummy frame to make it look like it has a caller. */
struct signal_frame_32 {
char dummy[SIGNAL_FRAMESIZE];
struct sigcontext sctx;
mcontext_t mctx;
/* We don't care about the rest, since IP value is at 'mctx' field. */
};
static inline int
is_sigtramp_address (unsigned int nip)
{
#ifdef SHARED
if (nip == (unsigned int)__vdso_sigtramp32)
return 1;
#endif
return 0;
}
struct rt_signal_frame_32 {
char dummy[SIGNAL_FRAMESIZE + 16];
siginfo_t info;
struct ucontext uc;
/* We don't care about the rest, since IP value is at 'uc' field. */
};
static inline int
is_sigtramp_address_rt (unsigned int nip)
{
#ifdef SHARED
if (nip == (unsigned int)__vdso_sigtramp_rt32)
return 1;
#endif
return 0;
}
int
__backtrace (void **array, int size)
{
@ -50,7 +93,28 @@ __backtrace (void **array, int size)
for ( count = 0;
current != NULL && count < size;
current = current->next, count++)
array[count] = current->return_address;
{
gregset_t *gregset = NULL;
array[count] = current->return_address;
/* Check if the symbol is the signal trampoline and get the interrupted
* symbol address from the trampoline saved area. */
if (is_sigtramp_address ((unsigned int)current->return_address))
{
struct signal_frame_32 *sigframe =
(struct signal_frame_32*) current;
gregset = &sigframe->mctx.gregs;
}
else if (is_sigtramp_address_rt ((unsigned int)current->return_address))
{
struct rt_signal_frame_32 *sigframe =
(struct rt_signal_frame_32*) current;
gregset = &sigframe->uc.uc_mcontext.uc_regs->gregs;
}
if (gregset)
array[++count] = (void*)((*gregset)[PT_NIP]);
}
/* It's possible the second-last stack frame can't return
(that is, it's __libc_start_main), in which case

36
sysdeps/powerpc/powerpc64/backtrace.c
View file

@ -18,6 +18,9 @@
#include <execinfo.h>
#include <stddef.h>
#include <string.h>
#include <signal.h>
#include <bits/libc-vdso.h>
/* This is the stack layout we see with every stack frame.
Note that every routine is required by the ABI to lay out the stack
@ -38,6 +41,27 @@ struct layout
void *return_address;
};
/* Since the signal handler is just like any other function it needs to
save/restore its LR and it will save it into callers stack frame.
Since a signal handler doesn't have a caller, the kernel creates a
dummy frame to make it look like it has a caller. */
struct signal_frame_64 {
#define SIGNAL_FRAMESIZE 128
char dummy[SIGNAL_FRAMESIZE];
struct ucontext uc;
/* We don't care about the rest, since the IP value is at 'uc' field. */
};
static inline int
is_sigtramp_address (unsigned long nip)
{
#ifdef SHARED
if (nip == (unsigned long)__vdso_sigtramp_rt64)
return 1;
#endif
return 0;
}
int
__backtrace (void **array, int size)
{
@ -53,7 +77,17 @@ __backtrace (void **array, int size)
for ( count = 0;
current != NULL && count < size;
current = current->next, count++)
array[count] = current->return_address;
{
array[count] = current->return_address;
/* Check if the symbol is the signal trampoline and get the interrupted
* symbol address from the trampoline saved area. */
if (is_sigtramp_address ((unsigned long)current->return_address))
{
struct signal_frame_64 *sigframe = (struct signal_frame_64*) current;
array[++count] = (void*)sigframe->uc.uc_mcontext.gp_regs[PT_NIP];
}
}
/* It's possible the second-last stack frame can't return
(that is, it's __libc_start_main), in which case

7
sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
View file

@ -34,6 +34,13 @@ extern void *__vdso_getcpu;
extern void *__vdso_time;
#if defined(__PPC64__) || defined(__powerpc64__)
extern void *__vdso_sigtramp_rt64;
#else
extern void *__vdso_sigtramp32;
extern void *__vdso_sigtramp_rt32;
#endif
/* This macro is needed for PPC64 to return a skeleton OPD entry of a vDSO
symbol. This works because _dl_vdso_vsym always return the function
address, and no vDSO symbols use the TOC or chain pointers from the OPD

16
sysdeps/unix/sysv/linux/powerpc/init-first.c
View file

@ -29,6 +29,12 @@ void *__vdso_clock_getres;
void *__vdso_get_tbfreq;
void *__vdso_getcpu;
void *__vdso_time;
#if defined(__PPC64__) || defined(__powerpc64__)
void *__vdso_sigtramp_rt64;
#else
void *__vdso_sigtramp32;
void *__vdso_sigtramp_rt32;
#endif
static inline void
_libc_vdso_platform_setup (void)
@ -46,6 +52,16 @@ _libc_vdso_platform_setup (void)
__vdso_getcpu = _dl_vdso_vsym ("__kernel_getcpu", &linux2615);
__vdso_time = _dl_vdso_vsym ("__kernel_time", &linux2615);
/* PPC64 uses only one signal trampoline symbol, while PPC32 will use
two depending if SA_SIGINFO is used (__kernel_sigtramp_rt32) or not
(__kernel_sigtramp32). */
#if defined(__PPC64__) || defined(__powerpc64__)
__vdso_sigtramp_rt64 = _dl_vdso_vsym ("__kernel_sigtramp_rt64", &linux2615);
#else
__vdso_sigtramp32 = _dl_vdso_vsym ("__kernel_sigtramp32", &linux2615);
__vdso_sigtramp_rt32 = _dl_vdso_vsym ("__kernel_sigtramp_rt32", &linux2615);
#endif
}
# define VDSO_SETUP _libc_vdso_platform_setup